; let compute = (function () {
    function plus(a, b) {
        return a + b;
    }
    function minus(a, b) {
        return a - b;
    }
    function mul(a, b) {
        return a * b;
    }
    function div(a, b) {
        return a / b;
    }
    return {
        plus: plus, 
        minus: minus, 
        mul: mul, 
        div: div
    }
})()